Last Night's TV: The Big Bang Machine, BBC4Lost Horizons: The Big Bang, BBC4The Wrong Door, BBC3

Next Wednesday at CERN, the giant multinational centre for nuclear research at Geneva, the Large Hadron Collider (LHC) will be switched on. The BBC has got itself into a bit of a lather about this, turning over large chunks of Radio 4's schedules to the event and sending Andrew Marr to broadcast on-the-spot reports, but so far hasn't explained in very great detail what it is we're supposed to be getting excited about. Professor Brian Cox cleared up that nicely in last night's The Big Bang Machine: on the one hand, there's nothing at all to get excited about; on the other hand, there's everything in the world, and I mean that most sincerely, folks.

There's nothing to get excited about because on Wednesday not very much will be happening. As one of his CERN colleagues explained to Professor Cox, the switch-on is not like a moonshot: you don't get a countdown and then push a big button. It's just a lot of computer programs running to prepare the machinery. This conversation took place in a room that didn't look too unlike mission control at Houston in Apollo 13, but on the day, there will only be two people on duty, one scientist and one technical person, together with about 200 others who will be coming along to watch. And even then, it's just a warm-up: the high-energy collisions of tiny particles that the LHC was designed to produce won't be taking place until next month. Radio 4 is doing is the equivalent of devoting a day to backstage reports from Glastonbury, without playing any music.

But then again, everything. For a start, there's the sheer scale of the LHC: a vast ring of concrete and steel, colder than deep space and lined with enormous arrays of the most sophisticated cameras ever built. And if it goes to plan, it will explain the fundamental workings of the universe. Years ago, the scientist J B S Haldane voiced the suspicion that the universe is not just stranger than we can imagine, but stranger than we're capable of imagining, and since then cosmologists and particle physicists have been engaged in an unofficial attempt to prove that, on the contrary, there are no limits to the strangeness of their imaginings, what with their multiple universes and vibrating multi-dimensional strings. You don't have to delve very deeply into the world of particle physics before parts of your brain start to shut down, in the interests of self-preservation.

As I understand it, though, the LHC is designed to re-create the conditions at the very start of the universe, an instant after the Big Bang. In particular, it should flush out something called the Higgs boson, a particle that only existed for a fleeting moment in the universe's history. If a Higgs boson does turn up, it will confirm that what physicists call the "standard model" is more or less right (the standard model strips the universe down to 16 very basic particles, much smaller than your average clod-hopping electron, and four basic forces). A Higgs boson no-show will mean that physicists have got things badly wrong. At least one of the senior scientists interviewed here was plainly much more excited by this prospect.

Professor Cox went through all this with enormous clarity (or then again, he didn't, and I've got it all wrong), as well as geniality. In a former life, he was part of the pop group D:Ream, and he still wears for the cameras a somewhat blissed-out expression, or maybe that's a smile of perpetual embarrassment about "Things Can Only Get Better" being adopted as an anthem by New Labour. He also offered reassurance, up to a point, that the LHC experiment will not create a series of black holes that will swallow the Earth, though I suspect viewers who had actually held on through the theory may have been a little anxious to notice that estimates of the probability of this happening here didn't get quite as low as zero.

Just before this programme, in Lost Horizons: the Big Bang, the physicist Professor Jim Al-Khalili went through the history of Big Bang theory from the 1940s to the LHC, using footage from old BBC science programmes, particularly Horizon. The clarity rating here was also high, but what I really noticed was how much more imaginative producers had to be about illustrating these things before they had the benefits of computer graphics. The Doppler effect, which allowed Hubble to realise that the universe is expanding, was demonstrated effectively using a small brass band sitting on a steam train. Even the music was better, with the old Radiophonic Workshop doing its futuristic twitters and drones. All Professor Cox got was the Penguin Cafe Orchestra playing "Perpetuum Mobile", the theme from a thousand adverts.

Meanwhile, The Wrong Door was advertised as a sketch show set in a parallel universe, but from the two episodes so far, it seems that in this new universe jokes do not exist. Instead, you have so-so CGI effects and the words "cock" and "piss" repeated at regular intervals. Try not to mention the words "big bang" in their presence.